Oscillograph sweep system



Dec. 29, 1953 R. M. PAGE OSCILLOGRAPH SWEEP SYSTEM Original Filed April 9, 1942 OSC/LLAT/IVG SWEEP CO/L WTOR MWLATOR IPMM mdmwrm M 1. 50mm erm JYNMMZAW 2 Sheets-Sheet l INVENTOR ATTORNEY Dec. 29, 1953 R. M. PAGE OSCILLOGRAPH SWEEP SYSTEM 2 SheetsSheet 2 Original Filed April 9, 1942 INVENTOR ATTORNEY Patented cs. 29, 1953 OSCILLOGRAPH SWEEP SYSTEM Robert M. Page, Camp Springs, Md. Driginal application April 9, 1942, Serial No.

1952, Serial No. 293,489

(Granted under Title 35, U. S. (30116 (1952),

' sec. 266) 4 Claims.

This invention relates to radio echo ranging apparatus and more particularly to an apparatus for producing indications of range and direction of remote objects.

This application is a division of my copending application Serial No. 438,321, filed April 9, 1942, and entitled Radio Echo Ranging Apparatus.

Certain radio echo ranging apparatuses disclosed in the prior art produce instantaneous indications on an oscillograph of the range of remote objects included within a limited field, and wherein measurements of azimuth of such remote objects are derived from the angular positino of the directional beam antenna with respect to a reference line. With a system of the foregoing type, when it is desired to determine the range of remote objects within a field extending 360 about the apparatus, it becomes necessary to rotate the antenna throughout 360 and to produce a diagram represent'ng remote objects at specific ranges and directions as indications thereof appear on the oscillograph for certain angular positions of the antenna. The foregoing method is not feasible, since a substantially long period of time is required to produce such a diagram,

ring which time remote objects previously detected and plotted will have moved from their previous position before the diagram is comp eted. rived from the angular postion of the antenna are not of a high degree of accuracy and consequently cannot be relied upon for controlling numerous instruments.

Other prior radio echo ranging apparatuses ,vide a sweep on the oscillograph which is caused to rotate in synchronism with the directional beam antenna from when representations of range direction of remote objects within field extending 358 about the apparatus may be more readily obtained. With the above type of tamed by rotatng Moreover, directional indications de- However, since 438,321. Divided and this application June 13,

Another object is to provide novel means for causing the beam of electrical energy to continually oscillate.

Another object is to provide a directional beam antenna coupled to a radio frequency transmittor for producing a beam of radio frequency energy with means associated with the antenna responsive to frequency modulation of the transmitter for deflecting the beam.

Another object is to provide an apparatus of the above type so characterized as to cause the beam to continually oscillate in response to contnuous periodic frequency modulation of the transmitter.

Still another object of the invention is to provide a directional beam antenna comprising a plurality of radiating elements or antenna sections with novel means serially feeding the antenna sections w'th the output of a radio frequency transmitter in such a manner that the current in each section is in the same phase as the current in other sections when the output of the transmitter is at a predetermined frequency, and including novel means for producing phase shifts of the current at each antenna section in response to var'ations of the frequency of the transmitter output for deflecting the beam.

Still another object is to provide an antenna arrangement having the foregoing characteristics with the means feeding the antenna sections comprising a plurality of transformer sections having equal values of Q positioned between the antenna sections.

Still another object is to provide a radio echo ranging apparatus including a directional beam antenna interconnected with a radio frequency transmitter for producing a beam of radio energy, with means associated with the antenna for causing the beam to continuously oscillate in response to continuous periodic frequency modulation of said transmitter, and the apparatus further including a sweep circuit for producing a radial sweep on an osc llograph rotating in synchronism with the antenna with means associated with the oscillograph for causing the sweep line to oscillate in synchronism with oscillation of the antenna beam.

Still another object is to provide an apparatus of the above type having a magnetic circuit associated with the oscillograph for producing a periodically varying magnetic field in accordance with the frequency modulation of the transmitter for causing the radial sweep line to continually oscillate, in synchronism with the beam.

Other objects and features of the invention will appear more fully from the following detailed description when con idered in connection with the accompanying drawings which disclose several embodiments of the invention. It is to be expressly understood, however, that the drawings are designed for purposes of illu tration only and not as a definition of the limits of the invention, reference for the latter purpose being had to the appended claims.

In the drawings wherein similar reference characters denote similar elements throughout the several views:

Fig. 1 is a diagrammatic showing of a radio echo ranging apparatus embodying the principles of the invention;

Fig. 2 is a diagrammatic llustrationof the propagation of the beam of electrical energy produced by the apparatus disclosed in Fig. 1;

Fig. 3 is a diagrammatic showing of a novel transmission line util zed in connection with the apparatus disclosed in Fig. 1;

Fig. 4 is a diagrammatic showing, partly in section, of a magnetic circuit arrangement associated with the oscillograph as shown in Fig. 1;

Fig. 5 is a cross-sectional view through line of Fig. l, and

Fig. 6 is a diagrammatic showing of the magnetic field produced by the circuit disclosed in Figs. 4 and 5.

With reference more particularly to Fig. l of the drawing, a radio echo ranging apparatus embodving the principles of the present invention is disclosed therein including a rotatable directional beam antenna ill, a radio pulse transmitter ii, a radio pulse receiver l2 and a suitable indicator such as a cathode ray oscillograph It. Radio pulse transm tter i! is t ned to a predetermined carrier frequency which is modulated bv a suitable high speed electronic kever M to generate a radio pulse output that is fed through a channel of duplexing circuit Hi to antenna Ill thus producing adirectional beam of radio energy comprising radio pulses that propagate at a predetermined rate.

Antenna H3 is to be of anv conventional directional tvpe having a pluralitv of radiating elements or antenna sections, not shown, While radio pulse transmitter H and radio pulse receiver !2 are to be designed in such a manner to respectively transmit and receive radio pu ses, such as the tvpe of transmitters and receivers employed in commercial television systems. Duplexing circuit l5 functions to automatically control individual connections between antenna is and the transmitter or receiver. A circuit constructed in accordance with the principles disclosed in the application of Leo C. Young and Rob rt M. Page, Serial No. 326,640,. filed March 29, 1940, for I111- pedance Control Coupling and Decoupl ng Systems adequately serves this purpose. When antenna ii! is so directed that the radio pulses emitted therefrom im inge upon remote obiects, the radio pulses are reflected from such objects in the form of echo pulses. The echo pulses are received at antenna lil, passed through another channel of duplexing circuit 55 to radio pulse receiver l2 wherein the echo pulses are suitably amplified. The output of receiver l2 is fed through capacitance l6 and applied on control grid ll of oscillograph 13.

In order to produce indications of range and direction of remote objects, in response to appli-- cation of echo pulses on grid ll, a sweep circuit is provided for producing a radial sweep or a radial trace e on the screen of oscillograph l3 which rotates in synchronism with rotation of antenna ill. As shown. in Fig. 1, a cylindrical deflection coil i3 is rotatably mounted on the oscillograph and is adapt-ed to rotate in synchronism with rotation of antenna H3. For this purpose, motor It is provided which rotates deflection coil 18, by means of shafts 2d and 2E, pinion 22 and annular gear 23, while synchronous rotation of antenna 19 is provided through reduction gearing 25. In order to produce a radial sweep on the oscillograph screen, saw-t0oth wave generator 25 is provided which supplies saw-tooth varying current to deflection coils IS with a suitable D. C. supply to produce a radial sweep which initiates at the center of the oscillograph screen. As in conventional radio echo ranging apparatuses, a suitable synchronizcr is provided in order to start each sweep line at substantially the same instant that radio pulses are generated at transmitter it so that accurate indications on range of remote objects may be obtained. Synchronizer 28 has connections with electronic keyer it and saw-tooth wave generator 25 in order to obtain such synchronous operation. With the foregoing arrangement, upon application of an echo pulse on grid El, a pulse indication appears on sweep line e at a distance from the center of the oscillograph screen that is a direct measurem nt of the range of the remote object from which the echo pulse was reflected, while the angular position of the sweep line, which corresponds to the angular position of antenna it, represents the direction of such object.

As stated heretofore, it is an object of the present invention to provide a radio echo ranging apparatus that is capable of producing persistent indications of range and direction of remote ob jects included within a field extending 369 about the apparatus. In order to accomplish the foregoing, novel means are provided for causing the beam of radio energy emitted from antenna is to continually oscillate in a fixed arc, at a high rate of speed, without movement of antenna it, so that the radio pulses will impinge upon remote objects included in the field of the are described by the oscillating beam. Such oscillation of the in Fig. 2

beam is diagrammatically illustrated wherein it represents the position of t 1 normal to antenna ill, when antenna iii, designated at point 11, is directed upwardly as viewed in the drawing, While 0 d rep "esent the p tions that the beam occupies at the outer e1; tremities of the angle 6 through which the beam continually oscillates. In accordance with the principles of the present invention, means are also provided for causing the radial sweep e produced on the screen of oscillograph it, to oscillate through an angle 0 equal to the angle thr ugh which the beam oscillates, as shown in Fig. l, and for causing the radial sweep, or trace 2 and the antenna beam, to oscillate in Echo pulse indications are thus produced on the osclllograph screen which correspond. to radio pulse reflections from all remote objects included in the angular field through which the beam oscillates. It is contemplated by the present invention to cause the beam of radio energy and the radial sweep to oscillate at a sufdcient rate of speed so that persistent pu se indications appear on the screen of the oscill-ograph. It is to be expressly understood, that with a construction of the foregoing character, persistent indications of range and direction of remote objects included in a field extending 369 about the apparatus may be readily obtained, since it would not be necessary to rotate antenna til at a very high rate of speed, as was necessary in prior systems. Continuous. oscillation of the antenna. beam through angle 9 allows, the speed of rotation of antenna to be substantially reduced whilestill maintaining persistent indications on the oscillograph. Moreover, with an apparatus including novel means for continually oscillating the antenna beam and the radial sweep in synchronisin, continuous scanning of a sector, equal to the through which the antenna beam oscillates, is obtained independently of the. speed of rotation of antenna l3. Also, by oscillating the antenna beam and the radial sweep line at a suficient rate, persistent indications of remote objects included within the,v angular field through which the antenna beam oscillates are. continually obtained independently of rotation of antenna ill.

Novel means, such as. claimed in my .ccpending application Serial No. 293,488, filed concurrently herewith as a further division. of my patent; application Serial No. 438,321., filed April 9, 1942, are associated with antenna It for causins thev beam of radio energy emitted therefrom to occupy a position a, as shown in Fig. 2, when transmitter H tuned to a predetermined carrier frequency, while causing the beam to deflect toward either position 0 or at when the carrier frequency of transmitter H is increased or decreased from such predetermined frequency. c

Such means functions, in response to variations of the carrier frequency of transmitter i l, to produce certain shifts in phase of the currents induced in the radiating elements or antenna sections of antenna lit for producing such antenna beam deflection. As will appear more fully hereinafter, the currents induced in the radiating elements are progressively shifted in phase in direct proportion to the extent of frequency variation from the predetermined or mean frequency value, with the currents progressively retarded or advanced in phasev in accordance with the direction that the. carrier frequency varies from the mean frequency value thereof. With reference again to Fig. 1 of the drawings, thev foregoing means comprises a novel transmission line which includes a series of feed lines 3| 32 and 33 each of which are connected to a radiating element or an antenna section of antenna 55. The output of duplexing circuit feeds into one end of transmission line So so that the various radiating elements of antenna 50 are serially fed with the radio energy output of transmitter ii. Transmission line 3t is shown in greater detail in Fig. 3. As shown, the transmission line is in the form of a concentric line comprising central conductor B t and an outside conductor 35, both having connections with duplexing circuit 55. Feed lines 3!, 32 and as are likewise disclosed as concentric lines having the central and outside conductors thereof respectively connected to conductors Sal and 35 of the transmission line. In order to more fully illustrate the manner that transmission line serially feeds the various radi'at ing elements of antenna to, feed lines 31, 32' and 33 are shown having connections with conventional dipole radiators each of whi h include radiating m mbers 36 and 3!. When dipole radiators are. utilized as radiating elements, feed lines. 3!, 32' and 33 are to be equal to quarter wave sections: of a. certain frequency, but it: is to be expressly understood that other types of radiat ing elements may be employed.

The novel means included in transmission line 30, that is responsive to variations of the carrier frequency of transmitter ii. for deflecting the. beam of radio energy, comprises transformer sections 3.8 and 39: which are respectively posi tioned between the central electrodes of feed lines 3.! and 32 and between the central electrodes of feed lines 32 and 33. In order to produce a beam of radio energy that extends outwardly from antenna it at right angles thereto, when the carrier frequency of transmitter ii is tuned to a predetermined frequency, transformer sections 38 and 39 are equal in length to an integral multiple of half-wave lengths, with the wave length corresponding to such predetermined frequency. With such an arrangement, when the carrier frequency is: equal. to the above mention d predetermined frequency, currents induced in feed lines 3 i, 32- and 3.3 and in the radiating elements respectively associated therewith, will be. in the same. phase relation with respect to current induced in the other feed lines, and consequently, the directional beam of radio energy of antenna ll! extends. outwardly therefrom at right angles thereto. In order to produce a progressive shift in phase along the series of feed lines 3!, t2 and 33, upon variation of the carrier frequency of transmitter H from the predeterr ed frequency value, transformer sections 35 and it are designed to have substantially large values of Q, since the value of Q determines the degree of phase shift for a certain. variation in frequency. Furthermore, transformer sections 38 and as are to have equal values of Q so that the degree of phase shift between adjacent feed lines or radiating elements are equal to thus obtain uniform progressive phase shift along the series of radiating elements which consequently produces a uniform deflection of the antenna beam. The value of Q for transformer sections 38 and. 39 is equal the. ratio of the characteristic impedance value and the load impedance value of the transformer sections. Since, as heretofore stated, transformersections 3.8v and 39 have equal values of Q, the ratios of the characteristic impedance values of the transformer sections to the load irn pedance values thereof, or to the impedance values at the points where the transformer sections. terminate, are also equal.

The foregoing may be more readily understood by designating hypothetical impedance values for certain elements of transmission line By assuming that the combined characteristic iznpedance of feed lines 3!, 32 and 33 the radiating elements 36' and 3? associated with each feed line is equal to 200 ohms, as seen looking toward radiating elements 35, 3i from points A, B or C, the load impedance of transformer section "it is thus equal to 260 ohms. By further assuming a 2 to 1 ratio between the characteristic impedance values of the transformer sections the irnpedance value at the points where such sections terminate, the characteristic impedance value of transformer section 3% will therefore be 3.00 ohms.

Since feed lines 32. and 83 are in parallel rela tion, the impedance value at point B, the point where. transformer section 33 terminates, or the load impedance of transformer section is equal to ohms. Continuing the same ratio of impedance values the characteristic impedance of transformer section is therefore 50 ohms. Furthermore, since feed line 35 is in parallel relation with feed lines 32 and 53, th impedance value at point C is approximately equal to can ohms, and, by utilizing a l ne from duplexing circult to having an impedance value eoual ap proximately to 66.6 ohms transmission line to is properly matched. It can be readily seen, therefore, with the foregoing assumed impedance values, that the values of Q for transformer sections 38 and 39 are equal. Such assumed impedance values, and resulting values of Q, are shown for purposes of clarity only, and are not to be construed as limiting factors. Moreover, the length of transformer sections 38 and 39 are not limited to integral multiple half-wave sections, but may comprise integral multiple quarter wave sections, in which case greater shifts in phase are obtained for certain impedance values and for certain degrees of frequency variation. It is to be expressly understood that the novel means included in transmission line 3%, for deflecting the antenna beam in response to variations of the carrier frequency, may be readily employed in a transmission line utilized for feeding a plurality of antenna radiating elements in parallel relation whereby antenna beam deflection in response to frequency variations may be obtained. In such an arrangement, the values of Q, for the transformer sections are selected to produce phase shifts of the currents induced in the radiating elements, in the same direction, upon certain variations in frequency.

When a source of radio energy, at a frequency corresponding to the wave lenrths of the integral multiple half-wave transformer sections 38 and 39, is applied to antenna if} through transmission line 39, the currents induced in feed lines 35, 32 and 33, and in the radiating elements associated therewith, are in phase with each other to thus produce a beam of radio energy which extends outwardly from the antenna at right angles thereto, as shown by beam at in Fig. 2. The dotted line .ry indicates the orientation of dipoles 35-3! at point '0. When the frequency of the source of radio energy applied to transmission line 30 is varied in a certain direction from the predetermined or mean frequency value, the currents induced in feed lines 3i, 32 and 33 are progressively advanced or retarded in phase along the series of feed lines. Such progressive phase variations of the currents applied to the feed lines and to the radiating elements associated therewith cause the beam of radio energy to deviate in a certain direction, toward position as shown in Fig. 2, for example, in direct proportion to the degree of progressive phase variation. Since transformer sections as and 39 are equal in lenrth to an integral multiple of half-wave lengths that correspond to the predetermined carrier frequency, transmission line will only have proper impedance matching when the radio energy applied thereto is at such predetermined frequency. When the carrier frequency of transmitter H is varied, transmission line becomes reactive,

and, since the values of Q of transformer sections 38 and are equal, such reactive effect uniformly progressively varies along the series of feed lines to thus produce the uniform progressive phase shift. As the frequency of the source of radio energy applied to transmission line 33 is varied in the opposite direction. from the predetermined frequency, a uniform progressive phase shift along the series of feed lines 3!, 32 and 33 occurs in a direction opposite the progressive phase shift mentioned heretofore thus causing the beam of radio energy from antenna it to likewise deviate in an opposite direction, toward position d as shown in Fig. 2.

In order to vary the carrier frequency of transmitter H, to carse the beam of radio energy to continually oscillate through an angle as indicated in Fig. 2, a suitable modulator 4c is provided. Modulator 40 is of such construction to periodically vary the carrier frequency of transmitter ll, about a mean frequency that is equal to the aforementioned predetermined frequency. Assuming the carrier frequency of transmitter I l to be equal to the above mentioned predetermined frequency the beam will occupy position a, as shown in Fig. 2. As modulator 4i operates, the carrier frequency decreases from the predetermined carrier frequency to deviate the beam toward the position thereof designated at c, and when the frequency is decreased to a value to deviate the beam a sufficient extent to occupy a position 0 modulator automatically functions to increase the carrier frequency of transmitter it, thus causing the beam to swing in the opposite direction until the opposite extremity of angle 0 is reached as shown by position d. Modulator M! thus functions automatically to periodically vary the carrier frequency of transmitter l i about a mean or a predetermined frequency. The carrier frequency is varied from the mean frequency to a certain frequency value less than the mean frequency and is then increased from the low frequency value to a frequency value greater than the mean frequency by a degree equal to the extent of frequency variation to the low frequency value. Since the carrier frequency of transmitter H continually varies between fixed frequency values that are equally greater and less than the predetermined frequency, the beam of radio energy from antenna ill continually oscillates through angle 0 as shown in Fig. 2. Modulator so also functions to modulate radio pulse receiver E2 in a corresponding manner. Modulation of receiver i2 is necessitated, since the echo pulses reflected from remote objects in cluded within the field through which the beam of radio energy continually oscillates are of different frequencies due to the frequency modulation of transmitter H. Therefore, by synchronously modulating transmitter H and receiver l2, the latter is rendered in a condition to receive and properly amplify the echo pulses of varying frequencies. If desired, receiver I? may be constructed in such a manner to possess sufiiciently broad band pass characteristics in order to be responsive to all the frequencies of the echo pulses, in which case, modulation of the receiver would not be necessary.

As stated heretofore means are provided for causin the sweep line of radial trace e produced on oscillograph l3 to oscillate, in synchronism with oscillation of the beam of radio energy, through an equal angle 0. As shown in Fig. 1, such means comprises a magnetic device t; rotatably mounted on oscillograph l3. Magnetic device ll is supplied with current from modulator 40, which varies in accordance with the frequency variations of tranmitter H, to cause the radial sweep line e to oscillate in synchronism with oscillation of the beam of radio energy, and the device is caused to rotate in synchronisrn with rotation of antenna it by means of annular gear 32 and pinion :33, the latter being connected to shaft 2 E. In Figs. 4 and 5 device i! is disclosed in greater detail. As shown, the device comprises acylindrical member 44, of insulating material, rotatably mounted on oscillograph if; by means of anti-friction bearings 45. Annular gear 42 is positioned on the outer periphery of member at and cooperates with pinion dB to cause the memher to rotate in synchronism with rotation of antemia H). Member is includes an upwardly extending cylindrical portion d6, likewise of insulating material, upon which is mounted a magnetic core 47 having a plurality of inwardly extending portions 38, disposed 90 with respect to each other and terminating adjacent oscillograph [3, as shown more particularly in Fig. 5. Core t"! may comprise a plurality of laminated disc-like members, or may be constructed of any suitable material. A plurality of coils it are associated with core 4?, each of which occupies a position between a pair of inwardly extending members 58. Coils :39 are connected in series and are alternately wound in opposition for producing alternate north and south magnetic poles at extending portions 3 when current of a certain polarity is applied thereto, and for reversing the magnetic polarity of the extending portions when current of opposite polarity is applied to the coils. Magnetic fields are thus produced between adjacent pairs of extending portions 48 with the direction of the magnetic lines of force thereof alternately varying as the polarity of the applied current alternates. As .shown in Fig. 1, magnetic device ll and deflecting coils is are mounted about oscillograph it in such a manner that radial sweep line e normally propagates, when no current is applied to coils in a direction toward an intermediate point on one of extending portions :33. Since magnetic device ll and deflection coils it rotate in synchronism about the oscillograph, the foregoing direction of propagation of sweep line e is continually maintained. When a source of current of a certaian polarity is applied to coils the magnetic field produced thereby between two pairs of adjacent extending portions as functions to uniformly deflect sweep line e in a certain direction, by an amount proportional to the value of the applied current. VJhe-n the polarity of the applied current is reversed, the magnetic lines of force between adjacent pairs of extending portions 33 likewise change direction to deflect sweep line e in an opposite direction.

In order to uniformly deviate radial sweep line in a direction proportional to the polarity and value of current applied to coils the strength of the magnetic field produced between adjacent pairs of extending portions 58 uniformly increases from the center of the oscillograph to the outer periphery thereof. As shown in Fig. 6, the magnetic lines of force I, between adjacent pairs of extending portions 3 are shown by broken lines having unequal radial distances therebetween in order to indicate the varying magnetic strength thereof. Core ll and coils dd associated therewith are to be of such construction that the strength of the magnetic fields are substantially zero at the center of the oscillograph, thus producing no force to deviate the sweep line at the beginning of propagation thereof, with uniformly increasing strength,- to uniformly increase deviation of the sweep line as the latter propagates toward the periphery of the oscillograph. When current oi a certain pola ity is applied to coils as the direction of the magnetic field between adjacent pairs of extending portions 18, as shown by the full arrows, deviates sweep line c in an upward direction, as viewed in the drawing; when the polarity of the applied current is reversed, the direction of the magnetic lines of force is likewise reversed, as shown by the broken arrows, to deviate the sweep line in an opposite direction to a position shown in broken lines. It is to be expressly understood, therefore, that the foregoing construction provides means for uniformly deflecting radial line sweep e, in direction and degree respectively proportional to the polarity and value of current applied to coils When modulator it is in a condition so that the output of transmitter i I is at the aforementioned predetermined carrier frequency the beam from antenna ill will extend therefrom at right angles thereto as shown by a in Fig. 2. At this instant modulator does not function to supply cu'ren-t to coils is and line sweep e on oscillograph i3 is not affected. However, as modulator ea functions to vary the frequency of transmitter ii to cause the beam from antenna ill to deviate in a certain direction, toward position c in Fig. 2 for example, modulator it simultaneously functions to supply a source of current, of a certain polarity to coils as at a rate proportionate to the degree of variation of the carrier frequency of transmitter I I. Such current supplied to coils d9 produces a magnetic field within oscillograph it that causes the radial line sweep e to deviate in a direction similar to the direction of deviation of the beam and by a corresponding amount. When modulator it functions to cause the antenna beam to deviate from the normal position thereof in 'a direction toward position at in Fig. 2, the polarity of the current applied to cells i l is reversed and applied thereto, at a rate proportional to the degree of frequency variation, to deviate radial line sweep e in a similar direction and by a corresponding degree. lviodulator thus functions to periodically apply varying currents of alternate polarities to coils as, while simultaneously periodically modulating the carrier frequency of transmitter it between certain frequencyvalues equal degrees greater and less than the meanor predetermined frequency value. The radial line sweep e produced on oscil-lograph I3 is therefore caused to continually oscillate through angle 0 in synchronism with oscillation of the beam of radio energy through an equal angle.

Operation of the radio echo ranging apparatus disclosed in Fig. 1 is as follows:

Modulator circuit ill functions to vary the carrier frequency of transmitter l l in such a manner that a beam of radio energy is produced which extends outwardly from antenna it and which continually oscillates through an angle 0 as shown in Fig. 2. Since modulator all also simultaneously supplies varying currents of alternate polarity to magnetic device ti, the radial sweep line e produced on oscillograph it, upon application of saw-tooth wave forms to deflection coils i8, oscillates through an equal angle "49, in synchron-isrn with oscillation of the antenna beam. Electronic keyer it functions to modulate the output of transmitter l I so that the beam of radio energy from antenna iii comprises radio pulses propagating at a constant rate controlled by synchronizer 26; the latter also functions to control operation of saw-tooth wave generator E5 in such a manner that the radial sweep lines are initiated at substantially the same instant that radio pulses are emitted from antenna Id. Whenever radio pulses emitted from antenna is in the foregoing manner impinge upon remote objects within the angular field through which the beam continually oscillates, the pulses are reflected from the objects in the form of echo pulses of certain frequencies determined by the frequency of the beam. Since radio pulse receiver i2 is modulated in synchronism with modulation of transmitter H, by means of modulator 35, the receiver is capable of responding to and properly amplifying the reflected echo pulses, although the latter are at different frequencies. It is to be expressly understood, however, as mentioned heretofore, that receiver l2 may be constructed in such a manner as to have suitable band pass characteristics so that the latter will respond to all frequencies within the range of frequency variation of transmitter H. The pulse output of receiver 52 is passed to grid ii of oscillograph l3 and echo pulse indications are produced on sweep line e in a manner well understood by those skilled in the art. Since generation of radio pulses and the radial sweep are properly synchronized, and, moreover, since the beam of radio energy and the radial sweep line e are caused to oscillate in synchronism, the pulse indications produced on radial sweep line or radial trace e correspond to range and direction of remote objects included within the angular field through which the beam oscillates from which echo pulses were reflected. Bias control 5% may be operated to reduce the intensity of the radial sweep line e so that only the echo pulse indications are produced on the oscillograph screen.

When antenna it is caused to rotate upon operation of motor i9, deflecting coil It as well as magnetic device 25 are caused to rotate in synchronism therewith. The oscillating beam of radio energy from antenna 55) is thus caused to rotate while the synchronously oscillating sweep line 6 is rotated in synohronism therewith. In this manner, radio pulses emitted from antenna it are caused to impinge upon all remote objects within a field extending 360 about the antenna and echo pulse indications thereof are produced on oscillograph it from which range and directional measurements may be obtained. If the antenna is rotated slowly, persistent vision of range and directional indications of such objects within an angular field 0 are constantly maintained since the beam is continually oscillating at a high rate of speed. In order to obtain persistent vision of all objects within the complete field of the antenna, the speed of rotation of the antenna, and consequently radial sweep line e, is increased. Since persistent vision of range and directional indications throughout an angle 6 is constantly provided, it is to be expressly understood that the necessary speed of rotation of antenna it, in order to provide persistent indications throughout 360, is substantially reduced with respect to the necessary speed required in apparatuses of the type wherein continuous beam deflection is not provided. The speed of rotation of the antenna is reduced a sufficient amount so that the same may be readily rotated at the necessary speed even though the antennae required for this type of apparatus are necessarily large structures. As mentioned heretofore, the intensity of radial sweep line e may be reduced by adjustment of bias supply E l so that only persistent indications of echo pulse indications are produced on the oscillograph screen. By employing suitable polar coordinates on the oscillograph screen, range and direction of remote objects corresponding to such indications may be accurately obtained.

There is thus provided by the present invention novel means for continually deflecting a beam of radio energy. Such means comprises a novel transmission line for serially feeding the various antenna sections or radiating elements of a directional beam antenna and for varying the phases of the currents induced in each section in response to frequency modulation of the radio frequency source supplied thereto, thus causing the beam of the antenna to oscillate in accordance with such frequency modulation. Moreover, the present invention provides a novel radio echo ranging apparatus employing the novel beam deflecting means noted above in connection with a novel device for causing a sweep line produced on an oscillograph to oscillate in synchronism with the beam. With this construction, persistent indications of range and direction of remote objects included in the field through which the beam oscillates may be obtained Without movement of the antenna construction. Also, such a construction reduces the speed of rotation of the antenna that is normally required to produce persistent indications of range and direction of remote objects inzluded within a field extending 360 about the apparatus.

Although several embodiments of the present invention have been disclosed and described in detail herein, it is to be expressly understood that various changes and substitutions may be made therein without departing from the spirit of the invention as well understood by those skilled in the art. For example, with reference to the novel transmission line disclosed in Fig. 3, it is to be expressly understood that the invention is not limited to the specific construction disclosed therein but that transformer sections 33 and 39 may have characteristic impedance values different from the values designated and may comprise quarter wave sections, while the transmission line may be constructed in such a manner to serially feed a directional beam antenna having any number of antenna sections or antenna radiating elements, or to feed any number of antenna radiating elements in parallel relation. Reference therefore will be had to the appended claims as a definition of the limits of the invention.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. In combination, an oscillograph tube, sweep circuit for producing a radial line sweep on said oscillograph, a magnetic circuit associated with said oscillograph, and means applying varying currents of alternate polarity to said magnetic circuit for producing an alternating magnetic field of continually varying strength within said oscillograph whereby the sweep line continually oscillates.

2. In combination, an oscillograph tube, a sweep circuit for producing a radial line sweep on said oscillograph, a magnetic circuit associated with said oscillograph, said circuit comprising a circular magnetic core positioned about said oscillograph, a plurality of pole members extending inwardly toward said oscillograph and angularly disposed about said oscillograph, a plurality of coils each positioned about said core between certain pairs of said poles, said coils electrically connected in series and alternately wound in opposition with respect to each other, means app-lying varying current of alternate polarity to said coils for producing magnetic lines of force between said poles in the plane of said sweep line, said lines of force alternately varying in direction and continually varying in strength for displacing the sweep line through a certain angle.

3. In combination, an oscillograph tube, a

sweep circuit for producing aradial line sweepon said oscillograph, a magnetic circuit asso= eiateci with said oscillograph, and means applying current at a varying rate to said circuit for prcducing magnetic lines of force within said oscillograph the strength of which varies in accordance with said varying current, the lines of force prepagating in such a manner to cfier no effect to displace the radial sweep line at the center of the oscillograph while offering gradually increasing displacement effect on the sweep line as the latter propagates toward the periphery of the oscillcgraph.

In combination, an oscillograph tube, a sweep circuit for procluczin a radial line sweep on said oscillcgraph, a magnetic circuit associated with said oscillograph, means applying 54 current at a varying rate to said circuit for producing magnetic lines of force within said oscillograph the strength of which varies in accordance with said varying current, the lines of force propagating in such a manner to offer no effect to displace the radial sweep line at the center of the oscillograph while offering gradually increasing displacement effect on the sweep line as the latter propagates toward the periphery of the oscillograph, and means alternately Varying the polarity of said varying current for causing said radial sweep to oscillate through a certain angle.

ROBERT M. PAGE.

No references cited. 

